It would seem to me that the added strength of the fin at the base could translate to more stress being put on the box itself and leading to more fin box blow outs. I have heard fins made out of some materials (composites) are designed so when too much stress is applied the fin snaps at the base instead of putting the stress on the glass causing cracks and damage to the board. Using a fin made of fiberglass, would seem to apply more force/ stress directly to the fin box due to the strength of the fin at the base. So what is ideal? A fin that breaks easily before the box (and the board) itself is damaged or one that will not snap as easily in the water but translates more stress to the box possible causing more blown boxes. JUst a thought. Soren
If you want drive out of your turns, weakening the base of your fins so they break first makes no sense. It’s kind of like useing plastic lug nuts on the wheels of your car, just so if you hit the curb you won’t hurt the rest of your suspension system as badly. The whole idea is surfing not playing bumper pool with the rocks. If you are going to have a sacraficial link it’s better to use the Lokbox tab that bends and lets the fin release. At least most of their fin support is in the tapered fit of the box and the fin root. Notching the side of fins at the base makes very little sense. Especially, when most collisions occur head on.
You didn’t mention the type of fin box.
If standard single longbox, there are a couple of options… buy fins with tab in front so it breaks off on impact or buy one of those plastic plates with brass threaded insert that pulls out on impact - the plastic plate won’t work if screw tab is in back.
Maybe we need a breakable pivot fin (plastic?) so rear screw tab fins can still release on impact? One bad feature of any of the longboard breakaway fins (plate or tab) is that they can jam the tip of the fin into the bottom of your board when they release.
Call me nuts, but I’d rather spend an hour and $5 on a box and $10 worth of glass & resin to fix a knock than lose a $60 fin…
The fin wouldn’t necessarily come out of the box… if the screw tab in front breaks or plastic plate insert pops, the fin just pivots on the cross pin as it releases.
A forward plastic cross pin would probably result in lost fin unless you rigged up some kind of mini-leash inside the box slot. This would probably break off the screw tab in the rear if hit with enough force.
Most of the damage I’ve seen form non-breakaway fins is at the front of the box and I’ve seen plenty of tails snap off completely right there.
Guys,
It would seem that the problem is not a fin or box too strong, but a board too weak.
Fin strength good.
Boxes and mounts into the board need to be engineered to withstand the stress of the fin.
If I am designing a fin and box system (I’ve done a few now), I want it to be robust against the most aggressive surfers possible. There are systems out there that are strong enough.
Knock-out fins with leashes. How long is it going to take to happen? No damage to fin, board, or body part.
blakestah, i actually broke a fin with your system the other day. overhead late drop and the cheapo $12 plastic fin gave way. i bruised my hip and would like you to know i am suing you!!!
not realy.
id like to have as strong a box/fin as possible and just stay away from situations the combo cant handle. im not a big fan of the straight off adolf approach of surfing anyways. where do you guys snap fins off other then turning? rocks? maybe a old beater board with plastic fcs if you know your gonna be surfing in 2" of water.